Question

Which of the following is used for testing the presence of glucose?

• A. Milon's reagent
• B. Benedict's reagent
• C. Lucas reagent
• D. Grignard reagent

Answer 1

The correct option is B

Benedict's reagent

Explanation for the correct option:

(B) Benedict's reagent

• Benedict's solution is used to test for simple sugars, such as glucose.
• It is a clear blue solution of sodium and copper salts. In the presence of simple sugars, the blue solution changes color to green, yellow, and brick-red, depending on the amount of sugar.
• Benedict's solution is a chemical reagent and complex mixture of Sodium carbonate(${\mathrm{Na}}_2{\mathrm{CO}}_3$), Sodium citrate, and Copper(II) sulfate pentahydrate(${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$).

Explanation for the incorrect options:

(A) Milon's reagent

• Millon's reagent is used to detect the presence of soluble proteins.
• A few drops of the reagent are added to the test solution, which is then heated gently. A reddish-brown coloration or precipitate indicates the presence of tyrosine residue which occurs in nearly all proteins.
• Millon's reagent is a solution of Mercurous nitrate$\left({\mathrm{Hg}}_2{\left({\mathrm{NO}}_3\right)}_2\right)$ and Mercuric nitrate$\left(\mathrm{Hg}{\left({\mathrm{NO}}_3\right)}_2\right)$ in Nitric acid$\left({\mathrm{HNO}}_3\right)$-containing little Nitrous acid$\left({\mathrm{HNO}}_2\right)$.

(C) Lucas reagent

• Lucas' reagent is a solution of anhydrous zinc chloride in concentrated hydrochloric acid.
• This solution is used to classify alcohols. such as primary, secondary, and tertiary alcohols.
• Lucas reagent is a solution of anhydrous Zinc chloride$\left({\mathrm{ZnCl}}_2\right)$ in concentrated Hydrochloric acid($\mathrm{HCl}$).

(D) Grignard reagent

• Grignard reagents are highly reactive organomagnesium halides formed by the reaction of magnesium metal with alkyl or alkenyl halides.
• Grignard reagents can be used for determining the number of halogen atoms present in a halogen compound.
• A Grignard reagent is a chemical compound with the general molecular formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl.
• Example $\mathrm{Cl}-\mathrm{Mg}-{\mathrm{CH}}_3$

Hence, option (B) is correct. Benedict's solution is used to test for simple sugars, such as glucose.